ROCK HILL, S.C. — Ted Cruz has faced attacks on his national security record before, but not in a place like this.

The Palmetto State has far more of a military presence than Iowa and New Hampshire. And some of Cruz’s votes on national defense — during his time in the Senate he’s joined with Sen. Rand Paul to slow military spending, and he was a key collaborator in reforming the PATRIOT Act — could put the Texas senator on defense. A fifth of 2012 GOP primary voters here identified as veterans, and thousands more of their family members and friends could be swayed on issues of national security, too.

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Several of Cruz's foes and a super PAC are already pouncing.

“He voted for budgets that would gut the military. He voted for the Rand Paul budget that guts our foreign aid. Any military person knows you better have a soft power approach, and this carpet bombing thing is just silly,” said Sen. Lindsey Graham (R-S.C.), a Jeb Bush backer, referring to Cruz’s comments that he would “carpet bomb” the Islamic State. “His inexperience and his libertarianism won’t play here.”

As for Paul, Cruz has a conundrum. He’s having to defend his past alliance with the anti-interventionist senator on defense issues, at the same time he's wooing Paul’s libertarian voters after the Kentucky senator dropped out last week. On Thursday, two former Paul aides endorsed Cruz and praised him for being the next-best candidate on foreign policy after Paul.

A super PAC called the American Future Fund is planning to spend $1.5 million on an ad blitz blasting Cruz as weak on defense. “Ted Cruz talks tough on national security. But look at his record," the narrator says, going on to link Cruz with Bernie Sanders, Edward Snowden and President Barack Obama.

The Texas senator has been trying for months to recalibrate his message, in response to a GOP electorate demanding tough national security positions at a time of rising terrorism fears. This week he labeled himself a “national security conservative” — albeit one who is still extraordinarily skeptical of military intervention.

“We will rebuild our military, rebuild our navy, our air force. We’ll expand and honor our commitments to our soldiers and sailors and Marines and the Coast Guard,” Cruz said at a rally in Myrtle Beach, his voice rising with applause from attendees.

But regardless of Cruz’s latest rhetoric, the attacks are coming fast. A source in Marco Rubio's camp noted that his operation has been “laying the groundwork for making this a big issue” for months in South Carolina, which, according to a 2013 Governing analysis, had 37,000 active military, compared with about 1,500 in Iowa and New Hampshire combined.

And as Rubio began crisscrossing the state attacking Cruz as Paul-lite, the state's top elected officials joined in, calling the Texas senator unfit to be commander in chief.

“From a voter’s perspective, Rubio's in a stronger position,” said Sen. Tim Scott (R-S.C.), who backs the Florida senator.

On the campaign trail Thursday, Rubio said Cruz made a “calculated decision to appeal to libertarians” early in his Senate career by voting against some foreign aid and defense proposals. Rubio, meanwhile, has often aligned himself with the hawkish Graham-John McCain wing of the party.

"To the extent Ted has had foreign policy experience, it’s been aligning himself with Rand Paul,” Rubio said. “I'm not calling anybody names, it’s not disrespectful … but we have a big disagreement."

Cruz spokesman Rick Tyler called that criticism “laughable.”

“I don’t know how lying about Ted Cruz’s record is going to help Marco Rubio. It hasn’t helped him so far; it’s not going to help him now,” Tyler said in a phone interview Thursday. “Marco Rubio’s foreign policy is military adventurism.”

Cruz is prepared to forcefully rebut Rubio at Saturday's debate in Greenville, South Carolina, aides said.

"This is something he takes personally," said a person close to Cruz.

Still, military issues are potent in the political debate here, and attacks from the likes of Graham can't be easily dismissed. Walter Whetsell, a veteran South Carolina Republican strategist who worked with Rick Perry’s campaign, said that Cruz’s record is going to be “a problem.”

“Our roots run very deep with regard to military issues,” Whetsell said in an interview. “What complicates this for Cruz ... is whatever folks say about Lindsey Graham, one thing is that no one challenges the guy’s credibility on military issues.”

Cruz plans to litigate accusations about his defense record in the lawyerly manner he often employs to deflect criticism. He and his aides argue that he actually supported raising military spending in 2015, when he backed a Rubio budget amendment that boosted defense accounts.

On the PATRIOT Act, Cruz has never backed away from the reforms he championed that ended bulk data surveillance, though he doesn't highlight that vote in stump speeches. When asked about Rubio’s contention that Cruz “voted to weaken” intelligence, Cruz usually says Rubio is distracting from his record on immigration.

And Rubio’s accusations that Cruz voted against military spending ring false, Cruz aides say, because he voted against policy bills, not funding measures, a nuance lost in attack ads.

“The reason the senator voted against the [National Defense Authorization Act] is indefinite detention” of Americans, said one top Cruz adviser of the senator's years-old campaign promise. "Every time that Sen. Cruz has had the opportunity to actually fund our troops … he has.”

Still, proving he'd be the best commander in chief of the lot is a tough sell for Cruz in South Carolina. While he has a 23,000-member “Vets for Ted” coalition and some military endorsements, he's not getting much cover from fellow politicians. His Senate colleagues aren't throwing him a lifeline: While Cruz has served on the Armed Services Committee for more than three years, McCain, that committee's chairman, called his work “nonexistent.”

“He voted against the defense bill on the grounds he was against ‘indefinite detention.’ I asked him: ‘Do you think these people should be released then, who have been judged too dangerous to release?’ He said: ‘I’m against indefinite detention,’” McCain recalled in an interview.

McCain, who boasts plenty of experience running for president in South Carolina, wouldn't offer a prediction as to how Cruz might fare here.

"l'll leave that up to the judgment of the voters," he said. "Ask Lindsey. He'll know."

Michael Crowley and Austin Wright contributed reporting from South Carolina.